ISLAMABAD (AP) — An official investigation into corruption allegations against Pakistan’s Prime Minister Nawaz Sharif and his family has found a "significant disparity" between their declared wealth and known sources of income.

Sharif, who has previously denied allegations of abusing his authority to enrich himself, has been under pressure since documents leaked in 2016 from a Panama-based law firm disclosed that his family had offshore accounts.

Sharif and members of his family have appeared before a team appointed by the Supreme Court to investigate their offshore companies. Sharif has faced corruption allegations since coming to power in parliamentary elections in 2013.

"There exists a significant disparity between the wealth declared by the respondents and the means through which the respondents had generated income from known or declared sources," the report said, according to a partial copy released to reporters.

At one point the report refers to the "irregular movement" of cash gifts and loans from companies based in Saudi Arabia, the United Arab Emirates and Britain to Sharif, his son and companies linked to them.

The report suggests that the courts pursue action based on a 1999 accountability law intended to help stamp out corruption. But the final decision rests with the Supreme Court, which will take up the case next Monday.

A minister from Sharif’s ruling party dismissed the report, saying its findings were "unsubstantiated."

"The report contains no substance of corruption, tax fraud or any wrongdoing," said Ahsan Iqbal, the minister for planning and development.

Talal Chaudhry, a party spokesman, denounced the probe as part of a "conspiracy" aimed at removing the premier from office.

The opposition seized on the allegations, however, with cricket legend-turned-opposition leader Imran Khan calling on Sharif to "immediately step down."

The Supreme Court meanwhile put Pakistan’s leading Jang newspaper group on notice for publishing a front-page story Monday suggesting it was based on content from the report, which had not been made public when the story came out.

The head of the investigation team told judges the paper’s report was false, according to several lawyers who were present at Monday’s court session. They spoke on condition of anonymity because they were not authorized to talk to the media.